bjoernager/rust
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Separate RemoveFalseEdges from SimplifyBranches

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Otherwise dataflow state will propagate along false edges and cause
things to be marked as maybe init unnecessarily. These should be
separate, since `SimplifyBranches` also makes `if true {} else {}` into
a `goto`, which means we wouldn't lint anything in the `else` block.
This commit is contained in:
Dylan MacKenzie 2021-11-30 10:14:50 -08:00
parent 6db0a0e9a4
commit bb27b05104
3 changed files with 38 additions and 15 deletions
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17
compiler/rustc_mir_transform/src/simplify_branches.rs
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@ -1,22 +1,21 @@
//! A pass that simplifies branches when their condition is known.
use crate::MirPass;
use rustc_middle::mir::*;
use rustc_middle::ty::TyCtxt;
use std::borrow::Cow;
pub struct SimplifyBranches {
/// A pass that replaces a branch with a goto when its condition is known.
pub struct SimplifyConstCondition {
label: String,
}
impl SimplifyBranches {
impl SimplifyConstCondition {
pub fn new(label: &str) -> Self {
SimplifyBranches { label: format!("SimplifyBranches-{}", label) }
SimplifyConstCondition { label: format!("SimplifyConstCondition-{}", label) }
}
}
impl<'tcx> MirPass<'tcx> for SimplifyBranches {
impl<'tcx> MirPass<'tcx> for SimplifyConstCondition {
fn name(&self) -> Cow<'_, str> {
Cow::Borrowed(&self.label)
}
@ -53,12 +52,6 @@ impl<'tcx> MirPass<'tcx> for SimplifyBranches {
Some(v) if v == expected => TerminatorKind::Goto { target },
_ => continue,
},
TerminatorKind::FalseEdge { real_target, .. } => {
TerminatorKind::Goto { target: real_target }
}
TerminatorKind::FalseUnwind { real_target, .. } => {
TerminatorKind::Goto { target: real_target }
}
_ => continue,
};
}